The nature of bacteria acquired in the health care setting differs significantly from bacteria found in a community setting, primarily in their resistance to antibiotic therapy. Abundant evidence exists, however, that the hospital environment itself contributes to the problem by harboring virulent strains of bacteria, fungi, and viruses, and that many disinfection methods commonly used are ineffective and may actually spread contaminants. These contaminants are present on objects used in the health care setting, and in particular, on medical devices or instruments. These instruments must be decontaminated between uses.
Many medical devices are reusable after decontamination. Along with such materials pathogens and other contaminants are introduced. Endoscopy involves looking inside the body. Many of these devices have lumens and other channels or passages in which blood, tissue, and other materials are introduced during medical procedures. Decontamination of lumens and other channels and passages is critical, but also difficult due to access.
Endoscopes are non-exhaustive examples of such devices. Endoscopy is a common procedure in modern medical practices. Endoscopy involves the use of an endoscope, which is an instrument used to examine the interior of a hollow organ or cavity of the body. Endoscopes are inserted directly into an organ. Channels in endoscopes are used to transport medical instruments and materials, such as gasses and fluids. Tissue and fluids from the patient, and associated pathogens, are introduced into interior channels of the endoscope during such procedures. These devices must be decontaminated between uses.
Examples of such devices are flexible and rigid endoscopes. Endoscopes are used to examine and surgically manipulate the sinus cavities, upper and lower gastrointestinal tracts, lung fields, larynx, and intra-abdominal spaces. Endoscopes may have interior channels or conduits that are difficult to reach and disinfect. Relatively straightforward methods exist to disinfect endoscopes, although the working life of the endoscopes is lessened by washing due to chemical degeneration of components of the endoscope. An ongoing problem has been the reliable disinfection of endoscopes that have interior channels. Channels are used to inject liquid irrigants, suction, and to pass flexible instruments such as biopsy forceps. Interior channels and chambers have represented a challenge to infection control efforts.
Ultraviolet irradiation, particularly in the C bandwidth (2537 Angstroms), when given in adequate doses is lethal to all known pathogens. Microbes are uniquely vulnerable to the effects of light at wavelengths at or near 2537 Angstroms, due to the resonance of this wavelength with molecular structures. For the purposes of this document, the term UV-C is used for a wavelength of light being utilized for its germicidal properties, this wavelength being in the region of 2537 Angstroms.
The United States Food and Drug Administration and the United States Center For Disease Control and Prevention define disinfection as the use of a chemical procedure that eliminates virtually all recognized pathogenic microorganisms but not necessarily all microbial forms (e.g., bacterial endospores) on inanimate objects. There are three levels of disinfection: high, intermediate, and low. High-level disinfection kills all organisms, except high levels of bacterial spores, and is effected with a chemical germicide cleared for marketing as a sterilant by the Food and Drug Administration. Intermediate-level disinfection kills mycobacteria, most viruses, and bacteria with a chemical germicide registered as a “tuberculocide” by the Environmental Protection Agency (EPA). Low-level disinfection kills some viruses and bacteria with a chemical germicide registered as a hospital disinfectant by the EPA. For the purposes of this document, “disinfection” includes all three of these levels.